Electronic switching system



Feb. 14, 195 c. 5. SHUMARD 2,146,862

ELECTRONIC SWITCHING SYSTEM Filed April 27, 1937 2 Sheets-Sheet l INVENT R CHARLES CSHUMARD ATTO R N EY Patented Feb. E4, 1939 UNIED STATES PATENT OFFICE Radio Corporation of America, a corporation of Delaware Application April 27, 1937, Serial No. 139,214

11 Claims.

This invention relates to electronic switching devices and is more particularly concerned with an arrangement whereby it is possible to control two, three, four or more circuits in such manner that the transient or other phenomena to be observed may, in efifect, be simultaneously viewed on the luminescent screen of a cathode ray image producing tube. These patterns which are to be viewed are of the recurrent type and provisions are made according to the present invention whereby a switch operation may take place at a frequency well above the frequency of persistence of vision so that by electrically controlling the rate at which the diiferent recurrent wave forms are switched or operatively connected to one of the deflecting circuits of the cathode ray image producing tube, it is possible to view and compare, if desired, the various recurrent wave forms one with the other.

In an arrangement of this type the rate at which the different recurrent phenomena are to be observed and the rate at which the switching of the application of the wave to one of the deflecting systems of the cathode ray image producing tube takes place is interlocked so that the directions along which the cathode ray beam is deflected are mutually perpendicular. In practice, it is usually desirable to so connect and arrange the connections that the various recur- .I-o rent phenomena which are to be observed shall be applied to the beam deflection control system of the cathode ray image producing tube as to deflect the cathode ray beam across the luminescent screen along the vertical path, while the :25 time during which each phenomenon is applied or impressed upon the deflection control for vertical deflection is coordinated with the rate at which the cathode ray beam is arranged to move in a substantially horizontal path from one edge of the luminescent screen to that edge opposite. This latter deflection is generally known as the time sweep and provisions are made according to the present invention by which the rate of application of the phenomena is definitely interlocked I?) with the time sweep of the cathode ray beam.

While it is usually preferable, as above stated, to

apply the time sweep in the horizontal direction in contrast to the vertical, of course, it is to be understood that the invention, as it will be explained, is not in any way limited to this form of connection and may readily be applied in the opposite manner that is, for example, the time sweep applied in a vertical direction and the recurrent phenomena applied in a horizontal di- 5 rection.

01.171-95) AUG 2 8 @4 5 According to the prior art various suggestions have been made whereby a plurality of recurrent phenomena may, in eirect, be observed simultaneously upon the luminescent screen of a cathode ray tube and the rate at which these ob- 5 servations are made to take place coordinate with the cathode ray beam deflection varied in accordance with time at some pre-established rate, it being understood that the time of commencement of reproduction of the recurrent phenomena 10 always commences at the same phasal position of the time sweep.

It has already been suggested in the prior art to provide switching arrangements of these general types and such switching arrangements while heretofore usually of the so-called mechanical type have also to a limited extent utilized purely electronic means. However, according to the prior art, these systems were more or less complicated and did not in most instances provide for the rapidity of switching the rapidly triggering or flexibility of operation necessary where a great number of recurrent phenomena are to be simultaneously observed.

The present invention, therefore, has as its primary aim and object the provision of circuits which are extremely flexible in nature and which are readily adaptable to use for electronic switching for the simultaneous observation of recurrent phenomena where a number of phenomena to be simultaneously observed shall be two, three, four or any reasonably given number, the upper limit, of course, being determinable largely by frequency limitations of the possibility of distinguishing each of the complete phenomenon with respect to each other in order that the desired comparisons may be made. Therefore, pro visions are made according to the present invention by which the rapidity of switching between the several phenomena to be observed may be readily accomplished through the use of grid controlled gaseous discharge tubes to which the recurrent phenomena to be observed are applied and which become sequentially operative to impress the several phenomena in sequence upon one of the deflection circuits of the cathode ray tube.

Still other objects of the invention reside in the provision of circuits for accomplishing the switching of the connection to be observed in sequence to the deflection circuits in a manner which is relatively simple and free from unusual complications and which at the same time will involve a minimum amount of equipment for utilization.

Still other objects and advantages of the inven tion will become apparent andat once suggest themselves to those skilled in the art to which the invention'is' directed by readingthe following specification and claims in connection with the accompanying drawings wherein;

,Figure 1 represents schematically a three-cir-' cuit electronic switch of the cathode shutot! tv e- 'Figure 2 represents a modification of the arrangement of Fig. 1 applied to an increased num--' ber of switch circuits, and shows particularly a modified form of coupling. I

,Figure 3 represents still a further modifica-Q tion; and

Figure 4 shows a form of switching arrangement particularly adapted to switching under between a ground H and the terminal points l3,- l5 and Hand capacity coupled by way of con- 1 densers' l4, 16, lit to the control electrode of three separateamplifying tubes l9, 2| and 23. In order I to regulate the signal intensity applied to each of v the controlelectrodes of the amplifying tubes i9, I 2| and 23, suitable potentiometer connections are provided at 24, 2,6 and 28. One end of each potentiometer being connected to the input terminal through the condensers andthe other end of each potentiometer is connectedthrough a portion ofa potentiometer '29 30-or 3! to oneterminal of a voltage source connected between ground and a" terminal point 32' or-as shown more particularly by the powcr'supply means of Fig. 2. There is also connected inparaliel with this path a second, path comprising a condenser 33 and resistor 34 as well as the portion of the potentiometer 28' and the connection point between the condenser 33 and the resistor 34 connects to the suppressor grid and the cathode of each of the amplifier tubes i9, 2! and 23.

While as shown each of these paths comprises potentiometers, condensers and resistances, it is, of course, to be understood that the values of these elements while usually made equal one to the other need not necessarily be so and the values assigned to the various elements of the circuit for convenience and for the purpose of disclosing suitable values of resistance and capacity which have been found to be satisfactory may be varied within reasonable limits without departing from the scope of the invention, the values being merely illustrative in nature and not in any sense limiting.

The output energy from the amplifying tubes l9, 2| and 23 respectively which have been supplied with plate voltage from a source connected between the ground I l and a terminal point 31 by way of a resistor 38 are all connected in parallel by way of the conductor 39 and capacity coupled by way of the capacity and resistor combination 40, M to the input circuit of a common amplifying tube 42 whose output, as will be hereinafter explained, is applied across one pair of the deflecting electrodes of a cathode ray tube. Under normal conditions of operation all of the tubes l9, 2| and 23 are maintained in a biased state so as to be inoperative to draw plate current except at times when suitable triggering by the electron switching arrangement, to be herein described, is provided. The triggering operation is accomplished accomplished by, connecting these screen elec-,

trodes respectively byconductors 1B, and,"

to suitable points on the electronic switching cir- I cuit Referring now to the electronic switching cirplurality oi. tubeslil, 5| and, 53 are provided which are equal in number to. the number of separate inputs or phenomena tobe observed. These tubes 49, 5| and 53 are arranged to become sequentially operative and to trigger-the amplifier tubes i9, 21 and 23 in a predetermined sequence controlled inaccordance with the sequenceof operation of the tubes-49, 5| and 53. The tubes ,43, 5! and 53 j g are Preferably oi. the grid controlled gaseous dis! charge type since tubes oi this nature when rendered operative have the property of substantially producing a uniiormvoitage drop for given.

current passing therethrough.

In the switching arrangement comprising the:

tubes 49, 5| and 53'the plate electrode-of each of these tubes is energized from a common plate voltage supply (not shown)connected between ground and a terminal connection point, 54.11.!" way of the switch 55 and theconductors 56 and I I 51 and allot the cathode electrodes connect to a ground point H" by way'of resistor elements. 6.2,

' cuit which-shall place the several tubes 13, 2| and I 23 in a state to become sequentially operative, a

60 and Iii.v The conductors l6, "and "connect I the screen electrodes 43, II and 35 of the tubes 13,, o

. 2i and 23 respectively totubes 49, SI and 53 and connect tothe cathode electrodes 52, 6,3 and 64' or these last named tubes. 'Ihc grid electrodes 65, 66 and 61 0! tubes 3, 5i and 53 are supp with suitable bias'from a source ,(not shown) 68 and poled negatively with respect to 68 by conof suitable resistor elements 56 that the grid is biased negatively relative to the cathode under conditions when switching or operativeness of each individual tube does not take place. Connected to the grid electrodes of each of the tubes 49, 5i and 53 by way 01' condensers II, II and i2 is an outer conductor 13 which connects to a terminal point H of a second switch 15. Also connected directly to the grid of one of the tubes 49, 5| or 53, or as shown specifically to the grid of the tube 53, is a second conductor 16 connected by way of a resistance TI to terminal point 18 of the switch arm I9. Each of the switches 55, I5 and I9 is arranged to be operated in unison and to be switched between each of the three contact points shown so that in the position which the switch 55 has been shown there is no connection between the source of plate voltage for the tubes 19, 5| and 53 connected at terminal point 54 and the complete arrangement is in an inoperative state. Similarly, there is no connection established from the conducting member I3 to the terminal point I4 and the arm of the switch 15 but at this time there is established a connection between ground ll" and the terminal point 13 by way of the arm of the switch I! and the grid electrode of the tube 53. This connection preferably being made through the resistor 11 to a. point on either side of the resistance 31.

Now to render the device operative the switches 55, I5 and 19 are moved in unison from the contact point at which the switch arms are shown to be resting over to the next adjacent point. In this instance plate voltage will be applied to each connected between groundand the terminal point of the tubes 49, 5| and 53 but there will be no connection established between the conductor 13 and the arm of the switch 15 although the connection between the ground point I I and the grid electrodes of each of these tubes by way of the contact point 18, the resistor 11 and conductor 16 is well established. The condition established by the switch resting in its median position in such manner as to connect ground through the switch 19 and thereby connect directly point 18 through the resistance 11, conductor 16 to the grid 61 of the tube 53 produces a condition of un-symmetrical biasing of this grid with respect to the undisturbed bias existing on the grids 65 and 66 of the tubes 49 and 5| In this manner the tube 53 is transferred for operation upon the simultaneous shifting of switches 55, 14 and 19 to the extreme right position. Moving now the switching arms so that each rests upon the terminal point furthest to the right from the position in which the switch arms are shown, it will be seen that plate voltage is still applied to the plate electrodes of each of the tubes 49, 5| and 53 but that now there has been established, by way of the arm of the switch 15, a connection from the conductor member 13 to the conductor 80 into which impulse switch:- circuit 8| by way of the potentiometer connection 82 shown as connecting with the cathode of the impulse developing tube 83 as will be hereinafter explained. But now the connection between ground II" and the grid electrodes of each of the tubes 49, 5| and 53 has been broken.

In moving the switch arms from the position shown to the third position to the right it will be seen that the electronic switching device comprising the tubes 49, 5| and 53 is progressively conditioned for operation because plate voltage is supplied. The bias-for rendering the several tubes inoperative is applied so that the sequence of operation is determined by the unsymmetrical bias on the grid of the tube 53. If now it is assumed that the switch arms have been moved to the furthest position to the right from that shown then it can be assumed, for instance, that the tube 53, for example, is first rendered operative to draw plate current. Thus immediately prior to this time there was applied to the grid 66 of tube 5| and grid 65 of tube 49 a biasing voltage from the source connected to the terminal point 58 which was applied through resistors 85, 8G and 81 so that the tubes 5|, 49 are non-conducting. However, if tube 53 is rendered conducting then it will be appreciated that there occurs through the tube 53 and the resistor 6| connected between it and ground a voltage drop equal to the anode voltage connected between ground II and the terminal point 54 for the several tubes 49, 5| and 53. The usual voltage drop to be expected in a grid controlled gaseous discharge tube of the type of tube 53, hereinabove described and which, for example, may be of the type known in the art as the RCA885, is of the order of 16 volts. A suitable voltage for the source connected between ground II and terminal point 54 is of the order of 116 volts and therefore there occurs across the resistor 5| when tube 53 is drawing current, a voltage drop of the order of 100 volts, assuming the values above suggested. This, therefore. carries the terminal point of the resistor 6| connected to the cathode 64 highly positive with respect to its previous condition and there is applied therefore through resistors 90, 86 and 81, since tube 5| is not drawing grid current, a positive voltage which opposes the voltage applied between ground I and the terminal point 68 to bias the grid of the tube 5|, and the tube 49 then com-- mences to draw plate current while the tube 53 ceases to draw plate current because the po tential of the cathode has risen so high with respect to its previous state that it approaches the anode potential and the tube ceases to operate. However, this operation is controlled more accurately as to time of occurrence by reason of the switch 75 being connected to the terminal point 14 and by way of the conductor 13 to the condensers 12, II and 10 and into the grid electrodes 61, 66 and 65 respectively of tubes 53, 5| and 49 which applies by virtue of the operation of the discharge tube 83 forming a part of the impulse sweep circuit which changes the potential at the point at which conductor 80 connected with the conductor 13 connects to the potentiometer 82, so that there is, in effect, applied to the grid electrodes of the tubes 49, 5| and 53 an auxiliary impulse transferred by way of the condensers 12, H and I and controls more accurately the time of operativeness of the tube The triggering tube 83 is also of the grid controlled gaseous discharge type and serves to discharge the charge which has accumulated in one of the condensers 81 having been charged from a potential source 88 by way of the resistors 89. The grid electrode of the tube 83 connects by way of the capacity coupling 90 and conductor 9| to the conventionally shown sweep circuit generator 92 for providing horizontal or time deflection across the deflector plates 93, 94 of the cathode ray tube 95 of which only the neck portion is shown. The sweep circuit generator 92 may be of the usual type and also comprises a condenser charged from a source of constant current and arranged to be discharged in accordance with some suitable controlling impulse such, for example, as a recurrent 60 cycle signal or other frequency signal by way of either a so-called high vacuum discharge tube or another form of electronic discharge device such, for example, as a tube of the gaseous discharge type hereinabove described. Such sweep circuits are well known in the art and require no further explanation being merely conventional in nature.

Whenever one of the tubes of the switching ring comprising tubes 49, 5| and 53 becomes operative and plate current is drawn from the source connected between the ground I! and the terminal point 54, as was above exp ained, the potential of the cathode of the tube instantaneously operative rises with respect to the plate potential because of the fact that very .little of the total voltage drop of the plate supplying volt-- age is impressed across the tube and therefore at this instant when any one of the tubes 49, 5| and 53 becomes operative by way of connection of the conductor 48, for example, to the screen electrode 45 of the tube 23 and to the cathode 64 of the tube 53, the screen electrode of the amplifier 23 is carried highly positive after having been biased high y negative so that the tube 23 draws plate current and by way of the capacity resistance coupling to the tube 42 the phenomenon applied at the terminal point I! is transferred and amplified through the tubes 23 and 42 to become impressed across the deflecting electrode pair 97, 98 of the cathode ray tube simultaneously with the application of the time deflecting voltage appearing across the electrodes 03, II. In a manner similar to that above described as soon as the tube It has drawn plate current and at a frequency determined by the circuit constants that is, for example, the resistors 8!, O6, 81, etc., and the frequency at which the discharge tube 83 operates and whose impulse is thereby impressed upon the grid electrodes 61 and the like, the several tubes ll, ll and 53 et seq. are sequentially rendered operative. When the tube BI is next rendered operative following an operation of the tube 53 by which is meant the drawing of plate current, the

tubes 23, 2| and I! again are sequentially rendered operative and the phenomenon impressed upon the terminal points l1, l and i3 and then again on ll are sequentially applied to the defleeting plate electrode pair 93, 94 of the cathode ray tube 9!.

While according to Fig. 1 the number of amplifler tubes I 9, 2i and 23 has been shown as being equal to the number of tubes H, 53 and II of the switching circuit, it is, of course, obvious that each of the tubes l9, 2! and 23 may be replaced by a pair of tubes connected in push-pull whereby their inputs are balanced relative to ground in the usual manner. If now, for a further understanding of this disclosure, it is assumed that the tube Si is inoperative then there is applied to the screen grid 45 of the tube 23, for example, a biasing voltage which is determined by the re-' sistance of the resistor 6i times the value of the biasing voltage negatively applied to the terminal 68 and between this terminal and ground all divided by the sum of the resistance values of the resistor BI, 90 and 85. The same conditions will also obtain throughout the remainder of the circuit with respect to other tubes so that during conditions of inoperativeness of the grid tubes l8, 2| and 23, there is applied to the screen grid electrodes a negative bias which is removed in sequence as the tube to whose cathode the screen grid is connected commences to draw plate current. Of course, under these conditions the bias- "ing voltages on the screen electrodes of the tubes I, II and 23 are applied at all times except when one of these tubes is to be brought to an operative state and, in this event, the tubes are consecutively rendered operative by the removal of the biasing voltage and the application of a positive voltage to the screen electrode to cause a relatively heavy flow of plate current.

Referring now to Fig. 2, there is disclosed an arrangement for switching and supplying signals to the deflection plates of a cathode ray tube and this arrangement represents a modification of that shown by Fig. 1. As was above suggested the electronic switching arrangement herein disclosed is adaptable for use with a considerable number of input signal sources and the switching may embody the sequential and consecutive switching of say 11 phenomenon to a load circuit.

By the arrangement disclosed by Fig. 2 there has been set forth an adaptation of the system of Fig. 1 expanded to include four separate signal sources controlled consecutively and sequentially by electronic switching apparatus. The general nature of this arrangement follows that shown by Fig. 1 insofar as it provides a common biasing source of energy for each of the several tubes of the electronic switch comprising the tubes 9, 53, ii and 49 and the control of the amplifying means is, as in Fig. 1, also of the cathode shut-of! type by which is meant that the control of the bias applied to the amplifier tubes is dependent upon whether or not the tubes of auaaoa the. switching arrangement are in a conducting (that is operating) or a non-conducting (that is biased or non-operating) condition. in contrasttothearrangementshownbyllg. iwhere thetubeflwastheiirsttubeofthesequenceto operate by the removal of the bias therefrom during the changing of the position of the switch II, provision is made for the use of a plurality of manually operable switches "I, "I, m and m for intiating the operation of any of the several tubes I", 49, II and II respectively. If desired an attenuator I with suitable matching impedancemaybeusedforsupplyingimpulsesfromthe sweep circuit .2 for initiating the operation. at the selected frequency of the sweep circuit.

The power supply I" purely of a conventional type with a good voltage regulation is arranged to supply operating voltages as was shown conventionally by the terminal point connections in Fig. 1. Throughout the remainder of Fig. 2 like partsofl'ig. lhavebeen referredtoby similar numerical indications and the additional tube necessary for the four-circuit switching has been referred to by numeral indications like the first tube but increased by one hundred.

In some instances it may be desirable to trigger an electronic switch from an alternating current supply of approximately sinusoidal wave form. Whllethis wouldnotbetheusualcase sinceit is more frequently desirable to provide a triggering impulse of steep wave front, a sweep circuit may be synchronized from an A. 0. supply source by providing an arrangement of the general type herein shown by Fig. 3.

Referring now to Fig. 3 the two tubes ill and I'll, each of which is preferably of the grid controlled gaseous discharge type, have their plate electrodes energized from a suitable source of alternating current input of an assumed voltage value c which is connected between the plate electrodes of the tubes I18 and i1! and a ground point I". Inc cathodes of the tubes in and I'll also connect to this ground point, either directly or through suitable resistors. The bias voltage ill supplied between the grid Iii of the tube "I and ground "I is soadiusted that when the A. C. input supplied at source I'Ii reaches a predetermined value the tube I19 momentarily becomes conducting with the result that a voltage drop takes place across the resistor I so that the terminal point of this resistor connected to the cathode of the tube I'll becomes highly positive relative to its previous condition and approaches the potential on the plate electrode of this tube. Due to the connection from the terminal of resistor I connected to the cathode of tube II! the gridelectrode "I of the tube I" has its eifective bias which has been supplied from the bias source I" lowered by way of the connection through the condenser I90 and the resistor I" to the grid electrode Ill by the voltage drop taking place under conditions of conductivity of tube I" through resistor Ill. Normally, the bias voltage ill exceeds the voltage I85 but when the effective bias applied to the grid Ill by the source Ill is lowered thetube I18 commences to conduct and draw current, and the tube I1! is substantially short-circuited. At this time the tube I'll is cut-oi! since only the voltage drop of tube I'll exists across the whole of the tube l1! shunt circuit. Tube "I will shut oi! shortly before the input voltage e supplied at Hi goes negative. In this manner it will be seen that one impulse per cycle of input is obtained at the output impulse terminals I82 and ill.

In this arrangement the resistor I11 serves to limit the current through the tube I18 and also serves to provide regulation. The resistors I81 and I86 limit the grid current flowing while the resistor I 88 serves as a coupling medium. Ac cording to usual practice the resistance I89 should usually be kept small and the resistors I11 and I88 may be of the same order. In accordance with this arrangement the time constant of the impulse produced across the output terminals I 82 and I83 by the connection made to the resistor I 89 is approximately equal to the sum of the resistance values I89 and I88 times the capacity I99.

A still further modification of the invention as applied to a two-circuit switch and wherein the control is provided from an A. C. source, such as a 60 cycle supply, has been shown by Fig. 4. Referring now to this modification of the invention the impressed alternating currents used both for power supply and for controlling the switching time provided for the observation of the two phenomena supplied at the terminal points I9I and I92 are connected at terminals I99 for the purpose of controlling this switching operation as well as for supplying through a suitable supply unit I 93 operating voltages. The impressed alternating currents applied at the terminals I 99 when used to control the operation of the switching of the impressed phenomena appearing at the terminals I9I and I92. For the purpose of providing the switching operation control from the A. C. supply and permitting the observation of at least a full cycle of the switch signal, the frequency of the switching voltage should preferably be a maximum of one-quarter of the switch signal frequency, since the transient switching time is an appreciable part of a cycle. Since such a frequency is usually not available whereas the 60 cycle A. C. is readily obtainable from the power supply the arrangement of Fig. 4 is suitable for obtaining this frequency relationship.

The oscillator tubes I94 and I95 (preferably of the type known in the art as 2A3) are connected with the plate electrodes connecting to opposite end terminals of the primary of the transformer I96 which is center-tapped back to the cathode. The transformer primary is shunted by a condenser I91 and cross-connected between the grid of tube I94 and the plate of tube I95 is a connection including condenser I98 of which the terminal connected nearest to the grid of tube I94 is connected by a resistor I99 back to the plate circuit. Similar connections including condenser I98 and resistor I99 are provided for tube I96. In thisarrangement the constants are preferably so chosen that the oscillator oscillates at an assumed frequency of 15 cycles, assuming the frequency of the A. C. supply at terminals I 99 to be 60 cycles.

A pair of gaseous discharge tubes 299 and 29I of the grid controlled type, such for example as tubes known in the art as the type 885, have their plate electrodes connected respectively to the end terminals of the secondary of transformer I96, across which is connected the condenser 292.

The phenomena applied at terminals I9I and I92 are supplied to the control electrode of tubes 293 and 294 respectively by way of the voltage dividers 295 and 296 and one ofthe grids of each of these tubes also connects with the plate electrode of the tubes 29I and 292. The grids of tubes 293 and 294 are suitably biased as shown and plate potentials for these tubes are supplied from the power supply I93. By way of the connection 291 from the cathode connection of tubes 299 and 29I the voltage drop from the plate to cathode of the tubes 299 and 29I may be utilized to bias the tubes 294 and 293 to control the operative periods of each. In accordance with the time periods when either of the tubes 299 or 29I is made conducting by virtue of the energy supplied at the terminal of the secondary of transformer I96 rising in the positive sense, either of the tubes 293 or 204 is positively biased and the signals impressed at the terminals I9I and I 92 are amplified and transferred by way of the parallel output connection 299 to the terminal points 2I9 and utilized either for the purpose of controlling the deflection of a cathode ray beam or for the purpose of determining which of the plurality of impressed signals is eiTective in the load circuit connected with these terminal points.

The arrangement for applying the biasing volt ages to the various grids of the tubes 293 and 294 are quite analogous to the arrangements already described and are not herein repeated again in detail. It will be seen that the resistors 2I I serve to limit the plate current flowing through the tubes 299 and 29I whereas the grid resistors 2I2 serve to limit the grid current. These values are not critical but by way of example may be of the order of 5000 to 15,000 ohms.

Referring now further to Figs. 1 and 2, it will be noted that in connection with Fig. 2 the impulse from the attenuator I64 is applied across the resistor I63 through the condensers I64, when the switch 19 is on the contact furthest to the right but otherwise through the resistor I63" and the manual switches where resistor I63 is preferably made equal to the resistor I63. This is in contrast to the arrangement of Fig. 1 where the impulse is applied only through the condensers 19, H and 12. With the arrangement of Fig. 2, the condensers I64 are not absolutely essential but serve to'decrease attenuation and the amount of impulse voltage required. Thus, at the higher frequencies the resistance I63 can be omitted and coupling established only by way of condensers I64, while at the lower frequencies only the resistance I63 need be usedf It may be further worth noting that with the arrangement of Fig. 2, that where the resistance 69 is relatively small relative to resistances 99 and 85, that the screen voltage on the tubes I9, 2|, etc., is substantially zero.

While in connection with the showing of Fig. 1 various values suitable for the various resistance and capacity elements shown have been tabulated immediately beneath the figure of the drawings, these values have been given merely by way of example and are not to be construed as limiting in any manner but rather as illustrative of one suitable set of operating constants. Further the general arrangement described by the several figures of the drawings herein, while having been illustrated, especially in connection with the simultaneous viewing of different patterns on a cathode ray tube screen, is in no sense limited to these applications. While it is not desired to specifically enumerate each of the possible uses of the invention, it might be pointed out that the amplifier tubes I9, 2I, etc., associated with the switching circuit, including the tubes 49, 5|, 53, etc., may be adjusted to supply from their plate mixing circuit stepped direct current voltages, either by adjusting each individual control grid bias, or by tapping the switch voltage for different screen grid bias to each amplifier tube. Further, by the use of the arrangement herein shown separate oscillators. amplifiers or other apparatus may be effectively switched by electronically switching some controlling voltages so that audio tones of different amplifiers, for 'example, could be observed at low frequency switching or musical tones could be produced.

Still other varied uses of the invention will immediately become apparent to those skilled in the art and therefore it is desired that the disclosure be construed as covering all forms of switching systems which fall clearly within the spirit and scope of the hereinafter appended claims.

what I claim is:-

1. an electronic switching device comprising a network including a plurality of electron tubes each having grid, cathode and anode electrodes, a common source of anode potential for all of said tubes, circuit connections including a plurality of resistance elements connectin the cathode electrode of each tube of the network to the grid of the next succeeding tube in the sequence and the grid of the last tube of the sequence to the cathode of the first tube of the sequence, a common source of voltage for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the several tubes inoperative, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw plate current, means for subsequently rendering the several tubes in the sequence sequentially and consecutively operative following the initial operation of the first tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a load circuit connected with the output of the amplifying means, means for normally maintaining the amplifying means inoperative and means for rendering the amplifying means sequentially and consecutively operative at time periods of operation of the sequentially operating tubes to connect thereby the amplifying means to the load circuit.

2. An electronic switching device comprising a plurality of thermionic .tubes arranged in a sequence, each of said tubes having grid, cathode and anode electrodes, 9. common source of anode potential for all of said tubes, a circuit comprising a plurality of resistance elements connecting the cathode of each of the tubes to the grid of the next succeeding tube in the sequence and the grid of the last tube of the sequence to the oathode of the first tube of the sequence, means for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes, means for reducing, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw platecurrent, means for rendering the tubes in sequence sequentially operative following the initial operation of the first tube of the sequence, a plurali y of sources of signal energy and amplifying means associated with each of the sources, a control from each of the individual amplifying means to one of the said tubes of the firstnamed sequence whereby the amplifying means are rendered sequentially operative in accordance with the operation of the tubes of the firstnamed sequence, a common output connection for all of the amplifying means, and a load circuit for utilizing the output of the said amplifying means, said load circuit comprising a cathode ray tube having deflection circuits for deflecting the developed cathode ray beam in a plurality of mutually perpendicular directions, and means for switching means for reducing,

supplying the output of the parallelly connected amplifying means to one of the deflection circuits of the cathode ray tube.

3. An electronic switching device comprising a plurality of thermionic tubes each having grid, cathode and anode electrodes and arranged to operate in a predetermined sequence, a common source of anode potential for all of said tubes, a circuit comprising a plurality of resistance elements connecting the cathode of each of the tubes to the grid of the next succeeding tube in sequence and the grid of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the tubes inoperative, means for reducing,'upon starting, the biasing voltage on one of. the tubes to a value to permit the tube to draw plate current, means for rendering the tubes in the sequence sequentially and consecutively operative following the initial operation of the first tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a control from each of the individual amplifying means to one of the said tubes of the first named sequence for normally maintaining the amplifying tubes inoperative and means for rendering the amplifying means sequentially operative at time periods coinciding with the periods of operation of the tubes of the first named sequence, a parallel output connection for all of the amplifying means, and a load circuit for utilizing the output of the said amplifying means.

4. An electronic switching device comprising a plurality of thermionic tubes each having grid, cathode and anode electrodes and arranged to operate in a predetermined sequence, a common source of anode potential for all of said tubes, a circuit comprising a plurality of resistance elements connecting the cathode of each of the tubes to the grid of the next succeeding tube in the sequence and the grid of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying cut-off biasing potentials upon the grid electrodes of all of the tubes for normally maintaining the tubes inoperative, means for reducing, upon starting, the biasing voltage on one of the tubes to a value to permit the tube to draw plate current, means for rendering the tubes in the sequence sequentially and consecutively operative following the initial operation of the first tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a control from each of the individual amplifying means to one of the said tubes of the first named sequence for normally maintaining the amplifying tubes inoperative and means for rendering the amplifying means sequentially operative at time periods coinciding with the periods of operation of the tubes of the first named sequence, a parallel output connection for all of the amplifying means, and a load circuit for utilizing the output of the said amplifying means, said load circuit comprising a cathode ray tube having deflection circuits for deflecting the developed cathode ray beam in a plurality of mutually perpendicular directions, and means for supplying the output of the parallelly connected amplifying means to one of the deflection circuits of the cathode ray tube.

5. The system claimed in claim 1 wherein said load circuit comprises a cathode ray tube, and means for supplying the output from the amplifier to the cathode ray tube to deflect the cathode ray beam developed therein in one of two mutually perpendicular directions.

6. The system claimed in claim 3 wherein said load circuit comprises a cathode ray tube, and means for supplying the output from the amplifler to the cathode ray tube to deflect the cathode ray beam developed therein in one of two mutually perpendicular directions.

7. A system claimed in claim 2 comprising, in addition, a sweep frequency generator for deflecting the cathode ray beam developed in the cathode ray tube in a direction perpendicular to the path of deflection initiated by the output of said parallelly connected amplifying means, and means interconnected between the sequentially operative tubes and the deflection control means for interlocking the sequential operation and the deflection control whereby the said tubes of the sequence are rendered sequentially operative at predetermined time periods in the deflection of the cathode ray beam in the direction perpendicular to the direction of deflection provided by the parallelly connected outputs from the amplifying means.

8. A system claimed in claim 4 comprising, in addition, a sweep frequency generator for deflecting the cathode ray beam developed in the cathode ray tube in a direction perpendicular to the path of deflection initiated by the output of said parallelly connected amplifying means, and means interconnected between the sequentially operative tubes and the deflection control means for interlocking the sequential operation and the deflection control whereby the said tubes of the sequence are rendered sequentially operative at predetermined time periods in the deflection of the cathode ray beam in the direction perpendicular to the direction of deflection provided by the parallelly connected outputs from the amplifying means.

9. An electronic switching device comprising a network including a plurality of electron tubes each having at least a control electrode, a cathode and an anode, a source of anode potential for all of said tubes, circuit connections including a plurality of impedance elements connecting the cathode of each tube of the network to the control electrode of the next succeeding tube of the sequence and the control electrode of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying cut-oiT biasing potentials upon the control electrodes of all of the tubes for normally maintaining the several tubes inoperative, switching means for altering, upon starting, voltage on one of the tubes to a value to permit the tube to draw current, means for subsequently rendering the several tubes in the sequence operative sequentially following the initial operation of the first tube of the sequence, a plurality of sources of signal energy and amplifying means associated with each of the sources, a load circuit connected with the output of the amplifying means, means for normally maintaining the amplifying means sequentially and consecutively operative at time periods of operation of the sequentially operating tubes to connect thereby the amplifying means to the load circuit.

10. An electronic switching system comprising the biasing a plurality of signal energy channels, a. relay device connected with each signal channel, a load circuit connected to be energized from the relays, a switching network including a. plurality of electron tubes each having at least a control electrade, a cathode and an anode, a source of anode potential for all of said tubes, circuit connections including a plurality of impedance elements connecting the cathode electrode of each tube of the network to the control electrode to' the next succeeding tube in the sequence and the control electrode of the last tube of the sequence to the cathode of the first tube of the sequence, means for supplying biasing potentials upon the control electrodes of all of the tubes for normally maintaining the several tubes in one of two equilibrium states of operativeness, switching means for altering, upon starting, the bias voltage on one of the tubes to a value to permit the tube to change to the other of the two equilibrium states of operativeness, means for subsequently changing the several tubes of the sequence to the last named equilibrium state of operativeness sequentially following the initial change in the operative state of the first tube of the sequence, means for normally maintaining each relay inoperative to energize its associated load circuit, and means provided by said switching network for rendering the several relays operative in sequence to energize the load circuit in accordance with the presence and absence of signals upon the plurality of signal energy channels.

11. An electronic switching system comprising a plurality of signal energy channels, a relay device connected with each signal channel, a load circuit connected to be energized from said relays, a switching network including a plurality of electron tubes each having at least a control electrode, a cathode and an anode, a source of anode potential for all of said tubes, circuit connections for connecting the cathode circuit of each tube of the network to the control electrode circuit of the next succeeding tube in the sequence and the control electrode circuit of the last tube of the sequence to the cathode circuit of the first tube of the sequence, means for supplying biasing potentials of one polarity upon the control electrodes of all of the tubes for normally maintaining the several tubes in one of two equilibrium states of operativeness, an impedance element connected in each cathode circuit, switching means connected with the impedance elements for altering, upon starting, the voltage on one of the tubes to a value to permit the tube to change to the other of the two equilibrium states of operativeness, means for subsequently changing the several tubes of the sequence to the last named equilibriumstate of operativeness sequentially following the initial change in the operative state of the first tube of the sequence, means for normally maintaining each relay inoperative to energize its associated load circuit, and means provided by said switching network for rendering the several relays operative in sequence to energize the load circuit in accordance with the presence and absence of signals upon the plurality of signal energy channels.

CHARLES C. I l v 

